This competing continuation proposal, Treatment of Pediatric OCD, addresses an important problem in the management of pediatric OCD, namely partial response to initial treatment with a serotonin reuptake inhibitor(SRI). For most pediatric OCD patients treated in the community, the first line initial treatment is monotherapy with an SRI. Recommended doses of these medications leave the great majority of patients with clinically significant residual symptoms. While OCD experts typically recommend augmenting SRI partial responders with cognitive-behavior therapy (CBT), this recommendation is seldom followed. An alternative augmentation strategy widely used in community practice but considered second-line by OCD experts is to add an atypical neuroleptic, such as risperidone (RIS), to SRI monotherapy. Because CBT and augmenting medications may differ in relative benefit and in risk, it is Imperative to conduct a well-controlled comparison of these two augmentation strategies against a control condition in the same patient population. The proposed study, which will be conducted at Duke University (John March), University of Pennsylvania (Martin Franklin) and Brown University (Henrietta Leonard), will meet this vital public health objective. Specifically, using a volunteer sample of 135 youth (45/site) age 8-17 with a primary DSM-IV diagnosis of OCD partially responsive to SRI pharmacotherapy, we propose to conduct a 5 year outcome study that will evaluate the relative efficacy of augmentation with: (1) OCD-specific CBT; (2) risperidone (RIS); and (3) pill placebo (PBO). We propose a balanced 3 (site) x 3 (CBT, RIS, or PBO) x 4 (assessment point) 12-week comparison of the three conditions. At study exit, all participants will be given clinical recommendations regarding further treatment based on their clinical status and will be followed up naturalistically for 12 additional months. PBO non-responders at the end of acute treatment will be given a choice of open treatment with either CBT or RIS delivered at no cost by the study team; non-responders to CBT or RIS will receive the alternative treatment delivered at no cost by the study team or, if they prefer, will be referred for community treatment. Blind assessments will be conducted for all patients at weeks 0, 4, 8, 12 (Phase I); the IE but not the patient will be blind for assessments during naturalistic follow-up, which will be conducted at 3, 6, 9 and 12 months post treatment. By examining the relative benefit and risk of CBT and RIS augmentation in the same patient population, the proposed study will provide an empirical basis for formulating practice guidelines. Health professionals then will be better able to advise their pediatric OCD patients regarding the management of partial response to SRls.